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Description

Adds a user-friendly warning message whenpersistence.existingClaim is set but will be ignored due to distributed mode deployment.

Motivation and Context

Problem Statement

Users frequently configurepersistence.existingClaim expecting it to work in distributed mode, but this parameter is silently ignored because:

• Distributed mode uses StatefulSet'svolumeClaimTemplates
• Multiple PVCs are required for erasure coding (minimum 4)
• Only a single PVC can be specified viaexistingClaim

This leads to:

• User confusion when their custom PVC is not used
• Unexpected fallback to default StorageClass (e.g.,/var/lib/rancher/k3s/storage in K3s)
• Difficult debugging with no feedback about ignored configuration
• Potential disk space issues on wrong partitions

Real-world example:
I deployed MinIO with a custom PVC pointing to an SSD I had mounted at/mnt/data. However, in distributed mode, myexistingClaim was silently ignored, and MinIO ended up filling the root partition (/var/lib/rancher/k3s/storage) instead, causing system issues.

Solution

Changes Made

1. NOTES.txt: Added conditional warning block that displays when:

   • mode: distributed AND
   • persistence.existingClaim is set

2. values.yaml: Enhanced documentation with clear warning comment explaining the limitation

3. User guidance: Provides actionable solutions:

   • Switch to standalone mode to use existingClaim
   • Use distributed mode with custom StorageClass

Warning Message Preview

WARNING: persistence.existingClaim is set but will be ignored in distributed mode.In distributed mode, MinIO automatically creates multiple PersistentVolumeClaimsusing StatefulSet's volumeClaimTemplates for erasure coding.Your specified PVC 'my-custom-pvc' will not be used.To use your existing PVC:  - Switch to standalone mode: --set mode=standaloneTo use distributed mode with custom storage:  - Specify a StorageClass: --set persistence.storageClass=<your-storage-class>For more information:https://github.com/minio/minio/tree/master/helm/minio#distributed-vs-standalone

How to test this PR?

Helm Lint

$ helm lint helm/minio==> Linting helm/minio1 chart(s) linted, 0 chart(s) failed ✅

Test Cases

Test Commands Used

# Warning appears correctlyhelm templatetest helm/minio \  --set mode=distributed \  --set persistence.existingClaim=my-pvc \  --show-only templates/NOTES.txt# No warning in standalone modehelm templatetest helm/minio \  --set mode=standalone \  --set persistence.existingClaim=my-pvc \  --show-only templates/NOTES.txt# Lint passeshelm lint helm/minio \  --set mode=distributed \  --set persistence.existingClaim=my-pvc

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Optimization (provides speedup with no functional changes)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• Fixes a regression (If yes, please addcommit-id orPR # here)
• Unit tests added/updated
• Internal documentation updated
• Create a documentation update requesthere